The invention relates to a weaving machine for the manufacture of leno cloths and to a needle bar for a weaving machine of this kind.
In a method for the manufacture of leno cloths, ground threads are guided, on the one hand, by a needle bar; and on the other hand leno threads are guided by a heald frame which is moved up and down as well as back and forth with respect to the needle bar. The vertically guided movement of the leno threads is a first component of movement, onto which a second component of movement is superimposed with the help of a suitably designed heald frame. The leno threads are laterally displaced by an insertion element of the heald frame, i.e. a displacement movement is carried out, so that the binding which is typical for the leno cloths arises through the change in position of the leno threads.
In every method for the manufacture of leno cloths a leno harness is used which consists of two elements, with the one element serving for the reception of the leno threads and the other for the reception of the ground threads. The element for the leno threads can for example be a guide bar or a leno thread heald frame (cf. DE-A-23 53 658). The element for the ground threads can for example be a needle bar or a ground thread element which simultaneously has the function of a reed (cf. DE-A-466 340).
A leno harness which comprises a series of ground needles is known from CH-A-120 231; an abutment lamella is in each case arranged between two adjacent ground needles for a reliable change of the leno threads. The ground needles and abutment lamella are clamped at their lower end in a carrier beam; at the upper end the ground needles are free and the abutment lamella are guided loosely.
Due to the constricted space conditions between ground needles and abutment lamella, there arises a mutual hindrance of the ground and leno threads during the change of the leno threads. Through this hindrance it can happen that individual leno threads are temporarily tensioned like a violin string during the change, and that after the hindrance has been overcome the threads dart upwardly and in so doing jump beyond the abutment lamella into a wrong position. Alternatively, as a result of the hindrance, the leno threads remain in the channel out of which they should depart so that the binding off of the weft thread cannot take place.